package com.jcl.tree.utils;

import com.alibaba.fastjson.JSON;
import com.alibaba.fastjson.JSONArray;
import com.alibaba.fastjson.JSONObject;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * @author 朝花不迟暮
 * @version 1.0
 * @date 2021/3/17 21:46
 */
public class Test1
{
    /**

     - listToTree
     - <p>方法说明<p>
     - 将JSONArray数组转为树状结构
     - @param arr 需要转化的数据
     - @param id 数据唯一的标识键值
     - @param pid 父id唯一标识键值
     - @param child 子节点键值
     - @return JSONArray
     */
    public static JSONArray listToTree(JSONArray arr,String id,String pid,String child){
        JSONArray r = new JSONArray();
        JSONObject hash = new JSONObject();
        //将数组转为Object的形式，key为数组中的id
        for (Object o : arr)
        {
            JSONObject json = (JSONObject) o;
            hash.put(json.getString(id), json);
        }
        //遍历结果集
        for (Object o : arr)
        {
            //单条记录
            JSONObject aVal = (JSONObject) o;
            //在hash中取出key为单条记录中pid的值
            JSONObject hashVP = (JSONObject) hash.get(aVal.get(pid).toString());
            //如果记录的pid存在，则说明它有父节点，将她添加到孩子节点的集合中
            if (hashVP != null)
            {
                //检查是否有child属性
                if (hashVP.get(child) != null)
                {
                    JSONArray ch = (JSONArray) hashVP.get(child);
                    ch.add(aVal);
                    hashVP.put(child, ch);
                } else
                {
                    JSONArray ch = new JSONArray();
                    ch.add(aVal);
                    hashVP.put(child, ch);
                }
            } else
            {
                r.add(aVal);
            }
        }
        return r;
    }
    // 测试代码如下
    public static void main(String[] args){
        List<Map<String,Object>> data = new ArrayList<>();
        Map<String,Object> map = new HashMap<>();
        map.put("id",1);
        map.put("pid",0);
        map.put("name","甘肃省");
        data.add(map);
        Map<String,Object> map2 = new HashMap<>();
        map2.put("id",2);
        map2.put("pid",1);
        map2.put("name","天水市");
        data.add(map2);
        Map<String,Object> map3 = new HashMap<>();
        map3.put("id",3);
        map3.put("pid",2);
        map3.put("name","秦州区");
        data.add(map3);
        Map<String,Object> map4 = new HashMap<>();
        map4.put("id",4);
        map4.put("pid",0);
        map4.put("name","北京市");
        data.add(map4);
        Map<String,Object> map5 = new HashMap<>();
        map5.put("id",5);
        map5.put("pid",4);
        map5.put("name","昌平区");
        data.add(map5);
        System.out.println(JSON.toJSONString(data));
        JSONArray result = listToTree(JSONArray.parseArray(JSON.toJSONString(data)),"id","pid","children");
        System.out.println(JSON.toJSONString(result));
    }
}
